Surgical cutting instruments in which an inner member is rotated within a tubular outer member are known in the art. Typically, the tubular outer member includes a distal end with an opening defining a cutting port or window and the inner member includes a distal end with a cutting tip for engaging bodily tissue via the opening. Proximal ends of the inner and outer members commonly include hubs which attach to a handpiece having a motor for rotating the inner member relative to the outer member. The distal end of the inner member can have various configurations dependent upon the surgical procedure to be performed, with the opening in the distal end of the outer member being suitably configured to cooperate with the particular configuration of the distal end of the inner member to cut, resect or abrade tissue.
Often the tubular inner and outer members are straight. In many surgical procedures, however, it is desirable for the cutting instruments to be bent or curved to access surgical sites which are generally not accessible with straight cutting instruments. For example, in arthroscopic knee, hip or shoulder surgery it is well known to use curved cutting instruments which can be positioned at various desired angles relative to the surface of the bone.
The present invention provides a flexible drill which includes a nitinol portion of the shaft, to increase the flexibility of the shaft while maintaining sufficient column strength for the instrument during a cutting/drilling operation. Also provided is a novel method of joining (welding) a nitinol portion of a shaft to an adjacent portion of a shaft formed of a dissimilar metal, for example, joining (welding) a nitinol portion of a shaft to an adjacent stainless steel portion of the shaft.